Electronics in medicine: Insulin pump design

This article focuses on what role electronics plays in the design of an insulin pump. It describes the purpose of an insulin pump, its overall workings, and the requirements needed for its design and its implementation.

Purpose of an insulin pump
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. It is secreted regularly within the body and aids in converting incoming glucose into energy. When a normal human being’s body cannot secrete enough insulin, his/her blood glucose level rises, resulting in many adverse medical conditions.

To treat this problem, certain medicines are used to trigger more insulin secretion within the body. However, this doesn’t suit many diabetic patients. Therefore, many of those suffering from diabetes take regular doses of insulin injections. The disadvantage of this approach is that the insulin is injected only in bulk at repetitive intervals and is not continuously mixed with blood as it when secreted during a body’s normal functioning. Today, many physicians recommend the use of insulin pumps, which are portable devices attached to the body permanently and deliver constant amounts of insulin to the body via a catheter placed under the skin. The functioning of an insulin pump closely resembles the way in which insulin is secreted normally.

Figure 1 shows how an insulin pump is interfaced with a human body.

Figure 1: Interfacing Insulin pump with the human body

As per today’s statistics, 366 million people around the world suffer from diabetes, yet only around 0.1 percent of them wear insulin pumps to treat it.

Hi Ewizz,
My girlfriend is currently using one of these insulin pumps and there currently is a supplematary device which contunuiously monitors blood glucose level which significantly reduces the need to prick your finger. However, it's still required to test 1-3 times a day to calibrate the glucose monitor in order to relay the correct readings back to the pump. Once the blood sugar levels are sent to the pump, the pump in turn will ask the user to verify the amount of insulin to apply for correction. I think this is interesting on its own. All of this communication is done wirelessly by the way.

that one is not the closed loop, I intended. In the link you gave the user still needs to prick the finger/skin to get some blood on the strip to measure the glucose level. which is not automated. coming to think of it I realize that a non invasive blood sugar monitoring mechanism is needed for this to work, which mostly doesnt exist.

Hi eewiz,
1. Yes, it is commercially available (https://www.accu-chekinsulinpumps.com/ipus/). This is for people with severe diabetes risks and who might have to take large dosages. The commercially available products do not have a closed loop system and the rate is adjusted through manual settings.
2. Yes, it is possible to implement a closed-loop system where we can involve the same chip to monitor current blood glucose level and accordingly adjust the flow rate. Here is a link about it:http://www.cypress.com/?rID=43661&source=header. Systems like this haven't yet come out in the medical industry.

oh ok.. theres no feedback mechanism to know the current blood sugar level of the patient.. it works as a linear open loop.. which is not impressive. if there was a sensor to detect the current blood sugar level and then push insulin accordingly, that wud have been interesting. For open loop drug delivery other mechanisms like micro needle patches are more convenient.